Electrical coil



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Filed May 25, 1955 lllllll-lll-llll Inl'llllllllll ll'lllllllll [.lll'lllllll'llu llllllll'llllilllll lll-ll'lll'llllll llllll'llllllll .ll'lllllll. lllull June 14, 1960 s. H. HORN ELECTRICAL con,

2 Sheets-Sheet 2 Filed May 25, 1955 United States Patent ELECTRICAL COIL Sheldon H. Horn, Huntsville, Ala., assignor to Western Electric Company, Incorporated; New York, N.Y., a corporation of New York Filed May 25, 1955, Ser. No. 510,917 '5 Claims. Cl. 317-158) This invention relates to electrical coils and more particularly to an electrical coil having an inner lead protected by extra insulation.

An object of the invention is to provide an electrical coil having an inner lead protected by extra insulation to prevent short circuiting thereof.

Another object of the invention is to provide a coil with a selected intermediate turn of the first layer of wire held against unwinding to permit a predetermined number of free turns of the first layer to be unwound and pulled out from the coil to form an inner lead therefor.

A method illustrating formation of the coil may include winding a first sheet of insulation on an arbor to form a core insulator having several convolutions and simultaneously interwinding several turns of a first layer of wire therewith to form an inner lead of the coil, placing longitudinally on the outer surface of the core in-t sulator a first insulating tape having adhesive along one marginal portion of the outer face thereof, winding the remainder of the first layer of wire on the core insulator and the insulating tape and in engagement with the adhesive on the tape, winding a sheet of insulation on the first layer of wire to form a first interlayer insulator, and Winding a portion of the second layer of wire on the first interlayer insulator. The method includes adhering a second insulating tape having adhesive on one face thereof to the first interlayer insulator and the wires thereon and in alignment with and in overlapping relation to the first insulating tape, winding successive layers of Wire and successive sheets of interlayer insulators until the coil is fully wound, winding an outer sheet of insulation around the last layer of wire and sealing it with the end of the wire extending from the end of the outer sheet to form the outer lead of the coil. The inner lead is then pulled out in an axial direction and unwound from between the convolutions of the core until it is stopped by engagement with the edge portion of the adhesive on the first tape to position the lead between the insulating tapes, and with the first insulating tape and the core insulator disposed on one side thereof and the second insulating tape and the first interlayer insulator disposed on the other side thereof to provide protective insulation for the lead. The inner lead and the protective insulating tapes are then pulled radially over the end of the coil to cause a slight flaring of the ends of the plastic insulator sheets projecting beyond the layers of wire in the coil, after which the ends of the plastic insulator sheets are heated and pressed to coalesce and seal the ends of the coil.

Other objects and advantages of the invention will become apparent by reference to the following detailed description and the accompanying drawings illustrating a preferred embodiment of the invention, in which Fig. 1 is a fragmentary front view of a coil winding arbor showing an initial stage of the coil winding operation with the core insulator and a portion of the wire wound on the arbor;

Fig. 2 is a view similar to Fig. 1 showing a first in- 2 sulating tape applied to the partially assembled coil and showing the first layer of wire wound thereon;

Fig. 3 is a view similar to Fig. 2 showing the first interlayer insulator on the partially assembled coil and a portion of the second layer of wire wound thereon;

Fig. 4 is a view similar to Fig. 3 showing the second insulating tape applied to the partially assembled coil and over the first tape and showing the remainder of the second layer of wire wound thereon;

Fig. 5 is a view similar to Fig. 4 showing the col assembly fully wound on the arbor;

Fig. 6 is an enlarged longitudinal sectional view of an end portion of the coil showing the inner lead before it has been unwound from the convolutions of the core insulator;

Fig. 7 is a view similar to Fig. 6 showing the inner lead wire after it has been unwound and prior to coalescing the ends of the coil;

Fig. 8 is a fragmentary front view of the coil with portions thereof broken away to show the inner lead after it has been pulled out of the coil;

Fig. 9 is an enlarged detailed sectional view of a portion of the coil taken on line 9-9 of Fig. 8 showing the inner lead after it has been unwound;

Figs. 10 and 11 are enlarged fragmentary perspective views of adhesive tapes for holding some of the turns of the inner layer of wire of the coil and for protecting the inner lead thereof; and

Fig. 12 is a fragmentary longitudinal sectional view showing the inner lead and the insulating tapes at the end of the coil after the end of the coil has been coalesced.

An electrical coil 15 embodying the invention is made by securing one end 16 of a wire 17 to an arbor 18 of a coil winding machine by any suitable means, such as a removable key 19, and simultaneously Winding the wire and a sheet of suitable insulation, such as cellulose acetate, to form a core insulator 23 of the coil with the end portion of the wire 17 interwound therewith to form the inner lead 24 of the coil. The wire 17 has a coating of enamel or other suitable insulation thereon. The core insulator 23 as shown herein has three convolutions, and three turns of the wire are interwound with the convolutions of the core insulator and a fourth turn of the wire is wound around the outside thereof as shown in Fig. 1 to form the inner lead 24. At this point the arbor is stopped and a first insulating tape 26 is applied longitudinally to the core insulator 23 with the end portions of the tape extending beyond the ends of the core insulator 23 and held in position on the arbor by pieces of adhesive tape 27. The insulating tape 26 may be made of any suitable insulating material, such as cellulose acetate or polyester terephthalate, and on one face thereof is applied a relatively heavy coating of adhesive 28 along one marginal portion thereof, leaving a bare marginal portion 29 along the opposite edge of the tape (Fig. 10).

Preferably, the tape 26 is made of cellulose acetate and has a thin strip of insulating material 30 (Figs. 8, 9, and 11), such as polyester terephthalate, adhered thereto and pressed tightly thereagainst to form the bare marginal portion adjacent the adhesive portion 28. The tape 26 is positioned with the adhesive portion 28 thereof directed outwardly from the core insulator and disposed along the upper marginal portion thereof as shown in Fig. 2.

The several turns of wire interwound with the core insulator 23 form the initial turns of the first layer 31 of wire and after the first insulating tape 26 has been laid on the core insulator 23, the remainder of the first layer of Wire is Wound on the arbor as shown in Fig. 2. A second sheet of thermoplastic insulation is then wound around the first layer of wire to form an interlayer insulator 32 which engages and adheres to the adhesive 28 not covered by the first layer of wire. A portion of the second layer 33 of wire may be wound over the first inter-layer insulator 32 to hold it in position as shown in Fig. 3. The arbor is then stopped and a second insulating tape 35 having a coating of adhesive 36 (Fig. 9.) on one face thereof is placed overthe first interlayerjnsulator 32 and the wound portion of the second layer 33 of Wire and in alignment with and in overlapping relation to the first insulating tape 26, and with the adhesive coating directed inwardly in engagement with theinterlayer insulator 32, the wound portion of the second layer 33 of wire, and a portion of the first insulating tape 26 extending beyond the insulator 32. V insulating tape adhered to the partially assembled coil in superposed relation to the first tape, the remainder of the second winding is wound thereon as shown in Fig. 4, after which successive layers 37 of wire are wound thereon, and after each layer of wire, a sheet of insulation which forms. an interlayer insulator 38 is wound thereon last or outer sheet 40 of insulation may be sufficie ntly long to form several convolutions with which the Wire 17 is interwound and with the wire extending from the end of the sheet 40 as shown in Fig. 5 to form the outer lead 41 of the coil. A suitable solvent or adhesive is applied to the edge portion of the outer sheet 4t} to seal it to the sheet.

After the wire 17 has been severed at a suitable distance from the coil to form the outer lead 41, the

'arbor is removed from the winding machine and the key 19 withdrawn therefrom to release the end 16 of the wire, after which the arbor is withdrawn from the coil assembly, which is then out along planes 42, 42 (Fig. 5) to trim the coil to a predetermined size with the insulators extending a predetermined distance beyond the ends of the layers of wire. The end 16 of the wire, as shown in Fig. 6, is then gripped by the operator and pulled away from the end of the coil to unwind and withdraw successive turns of the inner lead 24, which is then pulled taut in an axial direction, causing the wire 17 to bend adjacent the portion 45 of the wire which is gripped by the tacky adhesive coating on the insulating tape: 26 and is held against unwinding between the insulating tape'26 and the first interlayer insulator 32 (Figs. 2 and 8). As the lead 24 is drawn taut and the unwinding thereof is stopped by the engagement of the lead with the adhesive 28, a portion of the lead is positioned between the insulating tapes 26 and35 and is engaged and enclosed by the tape 26, the adhesive 28 thereon and the interlayer insulator 32 (Fig. 9). The inner lead 24 and the tapes 26 and 35' on opposite sides thereof are pulled radially outwardly about the end of the coil as shown in Fig. l2'preparatory to sealing the end of the coil, and the coil is then placed in a device for heating and coinpressing the ends of the insulating sheets projecting beyond the ends of the layers of wire to coalesce the ends of the coil.

The layer of tacky adhesive on the insulating tape '26 serves to grip and hold an intermediate turn of the first layer of wire and permit a predetermined number of turns the lead and the end turn and short circuiting therebetween during the coalescing of the ends of the coil.

While the drawings and description disclose winding a single coil of only four layers of wire for purposes of With the second until the winding of the coil has been completed. The I simplifying the disclosure, it will be understood that a plurality of coils of any number of layers of wire may be wound simultaneously in stick form and then cut into individual coils in a well known manner.

It is to be understood that the above-described arrangements are simply illustrative of the application of the principles of this invention. Numerous other arrange ments may be readily devised bythose skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

1. In an electrical coil, the combination of a core insulator, an insulating tape disposed longitudinally on said core insulator and having a coating of tacky adhesive along one marginal portion of the face thereof directed away from the core insulator, a wire forming a coil winding having a first layer of Wire wound on said core insulator and said insulating tape in engagement with the tacky adhesive on said tape, said wire having an end portion thereof forming a coil lead disposed on the insulating tape and extending along and adjacent to the marginal adhesive whereby said lead is maintained on an extra insulating strip to prevent short circuiting thereof, and a sheet of insulation around the first layer of wire and a portion of the lead and in engagement with portions ofthe tacky adhesive on said tape.

2. In an electrical coil, the combination of a core insulator, a first insulating tape disposed longitudinally on said core insulator and having a coating of tacky adhesive along one marginal portion of the face thereof directed away from the core insulator, a wire forming a coil winding having a first layer of wire wound on said core insulator and said insulating tape in engagement with the tacky adhesive thereon, said wire having an -end portion thereof forming a coil lead disposed on the insulating tape and extending along and adjacent to the marginal adhesive whereby said lead is maintained on an extra insulating strip to protect and prevent short circuiting of the lead through the core insulator, a sheet of insulation around the first layer of wire and the lead and in engagement with portions of the tacky adhesive on said tape, and a second insulating tape having adhesive on one face thereof adhered longitudinally on said sheet of insulation in alignment with and overlapping relation to said first insulating tape to protect and prevent short circuiting of the lead to successive coil windmgs.

3. In an electrical coil, the combination of a sheet of V insulationforming a core insulator, a wire forming a coil winding on said core insulator and having a plurality of superposed layers of wire including a first layer on said core insulator and with a portion of the wire of the first layer extending therefrom to form a lead, sheets of insulation between-said layers of wire, and an insulating strip disposed longitudinally on said core insulator under said first layer of wire having a coating of tacky adhesive along one margin on the radially outwardly disposed face of the strip for engaging and holding the first turn of wire of said first layer, said lead positioned on the strip and extendingalong and adjacent to the marginal adhesive whereby said lead is maintained on an extra insulating strip to prevent short circuiting thereof, the ends of the core insulator and the sheets of insulation of said coil being coalesced with the end portion of the insulating tape and a portion of the lead wire being positioned around the end of said coil and directed away from the axis thereof.

4. In an electrical coil, the combination of a sheet of insulation forming a core insulator, a wire forming a coil winding on said core insulator and having a plurality of superposed layers of wire including a first layer and a second layer and a With a portion of the wire of the first layer extending therefrom to form a lead,

' sheets of insulation between said layers of Wire forming interlayer insulators including a first interlayer insulator disposed between said first and said second layers of wire, a first insulating tape disposed longitudinally between said core insulator and said first layer of wire, said first insulating tape having a coating of tacky adhesive along one margin on the radially outwardly disposed face thereof for engaging and holding the wires of said first layer and engaging portions of said first interlayer insulator, said lead positioned on the first tape and extending along and adjacent to the marginal adhesive whereby the lead is maintained on an extra insulating strip to protect and prevent short circuiting thereof through the core insulator, and a second insulating tape disposed longitudinally on said first interlayer insulator in alignment with and overlapping relation to said first insulating tape to protect and prevent shirt-circuiting of the lead to successive coil windings.

5. In an electrical coil, the combination of a core insulator, a wire forming a coil winding on said core insulator and having a plurality of superposed layers of wire including a first layer and a second layer and with a portion of the wire of the first layer extending therefrom to form a lead, sheets of insulation between said layers of wire forming interlayer insulators including a first interlayer insulator disposed between said first and said second layers of wire, a first tape of insulation disposed longitudinally on said core insulator between said core insulator and said first layer of wire, said tape of insulation having a coating of tacky adhesive along one margin on the radially outwardly directed face thereof for engaging and holding the wires of said first layer and engageable with a portion of said first interlayer insulator, said lead positioned on the first tape and extending along and adjacent to the marginal adhesive whereby the lead is maintained on an extra insulating strip to protect and prevent short circuiting thereof through the core insulator, and a second tape of insulation having adhesive on one face thereof and adhered longitudinally on said first interlayer insulator in alignment with and overlapping relation to said first tape of insulation to protect and prevent the lead from short circuiting from successive coil windings, the ends of the insulators being coalesced with the end portions of the first and the second tapes of insulation and the lead wire therebetween being bent around the end of said second layer of wire and directed from the axis of the coil.

References Cited in the file of this patent UNITED STATES PATENTS 1,815,620 Horn July 21, 1931 2,118,924 Henderson May 31, 1938 2,122,894 Sager July 5, 1938 2,166,841 Helgason et al. July 18, 1939 2,241,761 Blaisdell et a1 May 13, 1941 2,460,556 Wagar Feb. 1, 1949 2,488,468 Dinion Nov. 15, 1949 2,691,811 Wagar Oct. 19, 1954 2,728,879 Erikson Dec. 27, 1955 

